In traditional ultrasound imaging and display, color Doppler imaging (CDI), spectral Doppler imaging (SD), or B-mode imaging are available. CDI refers to color Doppler F-mode imaging techniques. CDI provides a qualitative evaluation of fluid dynamics and tissue motion in a body that is imaged. Thus, CDI techniques currently provide the user with limited quantitative information. B-mode imaging, with the associated gray-scale display, also provides a qualitative display with limited quantitative information. SD, on the other hand, provides the user with information about a single point or position in space. SD provides flow information as a display of the brightness of the spectrum and a velocity scale display.
Quantitative calculation of a surface integral or area average for a particular region of interest provides a measurement-based calculation--Doppler energy or power related to the amount of blood in a cross-sectional area or volume of tissue in the body. "Approximate Quantification Of Detected Fractional Blood Volume And Perfusion From 3-D Colorflow And Doppler Power Signal Imaging" by Carson et al., 1993 Ultrasonics Symposium, pp. 1023-26 discusses such a calculation. The article by Carson et al. discloses a signal power-weighted color pixel density calculated by summing the Doppler energy for the various pixels in the region of interest and dividing by the number of such pixels.
Limited use of linearization of B-mode data to aid in quantification is known. In U.S. Pat. No. 5,235,984 to D'Sa, a method for undoing the log compression and other processing to generate a linearized average of B-mode intensity in a region of interest is disclosed. D'Sa discloses averaging B-mode intensity for a region of interest and then linearizing the average B-mode intensity value. The quantified B-mode data is displayed. D'Sa also teaches a display of multiple B-mode intensity curves from sequential trace operations at one or more regions of interest.
Other techniques to aid quantification of Doppler velocity are known. One way to acquire Doppler velocity information and process the Doppler velocity information is by a one-dimensional histogram. The Doppler velocity histogram may then be displayed on an ultrasound display with the color display.
The color display of Doppler data is controlled by application of a threshold. Once color Doppler data of a particular parameter is obtained, the data is mapped to a color display. Before mapping, a threshold for the same particular parameter is applied to the data so that only data with a value above the threshold remains. Thus, the thresholded values are used for any calculations.
None of the ultrasound systems for obtaining and displaying ultrasound data is entirely satisfactory. As discussed above, only limited quantification is known. It is therefore desirable to provide an improved ultrasound system for obtaining and displaying ultrasound data.